Telephone receiver



July 21, 1931. A. A. DUNCAN TELEPHONE RECEIVER vFil ed Feb. 27. 1928 Am /5,440 ,4. auxvcm M 6. sm

ATTORNEY Patented July 21, 1931 UNITED STATES ARGHIBALD A. DUNCAN, 0F AKRON, OHIO TELEPHONE RECEIVER Application filed February-27, Serial 1 111 0. 257,183.

This invention relates to electromagnetic sound reproducing apparatus and particularly to telephonereceivers, radio loud speakers and other amplifying, sound reproducing devices of a like character.

,Objects of the invention are to provide a receiving apparatus of simple construction which can be economically manufactured and which will reproduce sounds in a clear,distinct manner. V

Aiurther object istoprovide a' sound reroducing apparatus which includes a diaphragm actuated by opposed electromagnetic ,circ'uits' arranged to utilize the full power of each mag etand to thereby provide means for' reprodiicing sound with considerable volume and without distortion.

Other objects and advantages will be readily apparent from the follcwing descrip- "'tion in which refe ences made to the accompanyi g drawings in which I have llustrated a form of 'the invention, it being understoodthat the invention is capable'ofvaiI'iOfiS adaptations and that changes and modifications may be madeor resort had to siibstitutions which come within the scope of the claimshereu'nto appended.

In the drawings 5 Fi ure 1 is a perspective view somewhat diagrammatic in character illustrating'the combination and arrangement of part's em ployed' in carrying out'the invention,

Figure 2 is a central, cross sectional View of telephone receiver constructed in ,accordance'with this inventio'nrthe sections of the various parts shown in ,Fig1ir e 1, being taken as indicated by the lines 2 2 shown her Figu'r'e3- is a similar, sectional view taken as indicated by the lines 33 of Figure 1,

Figure iis a perspective yiew showing a modifi d form of the invention.

The invention will now be described with reference to thepa'rticularadaptation thereof -illiis'trate'd in the drawings, in which like characters of reference are employed to designat like parts as the same may appear in any of the several Views:' The numeral 5 denotes a casing which may be ofanysuitable form and is preferably composed of brass or other non-magnetic material. The casing 5 is exteriorly threaded and'fa cap or closure member 6 is operative-1y secured thereon. The numeral 7 denotes a diaphragm which is positioned against the open end of the casing 5fl'and is secured in place thereonby being engaged bythe cape. The cap 6 is provided with a suitable threaded opening 8 throughwhich the soundwayes may pass or nt which m y b mo n edah r tubular extension. I I

The numeral 9 denotes a copper plate which is secured to the bottom of the casing 5. An electromagnet 10 is uitabl seured tothe plate9 so as to ex'tend froi'n one side thereof to et point approximatel central thereof; The magnet comprises a coil 10a ofcopper wh ieh is wound around asoft iron core 106. The core lobis secqr d'atthe bottom thereof to a soft strip 1 6. A siniilar core l0d is secured in an upright position to the strip 100' at a point adjacent the other end thereofan'd a coil lOe ofcopper wire is wound around the core 10d. The arrange ment is such that the core 10d positioned in coaxial alinement withthe diaphragm 7. Thereference characters 10; denote a like strip of soft iron which is suitably secured to the top of the core 10?) and projects over the top ofthe coil 106 in spaced relation thereto. .Thec'oils 10a and 106 are wound so. that thes'trip 10f becomes a south pole andithe upper end of thecore 10d becomes a north pole; Thes'trip 10; is provided at a point adj acent the free end thereof with an opening logj'for a "purpose to be hereinafter described. structurecomprising the "strips 100 and 10f,.the cores 10b andlOd and the coils 10a and 10g comprise a magnetic circuit having aga 11.

The numeral 13 denotes a core which is wound wither surrounded by an electromagnetic coil l2'which is preferably composed of copper wire. An extension .14 of soft iron is secured to one endtof the core 13 and the extension 15 is securedgtothe other end thereof. A vibratory reed 14a composed ofsoft iron is secured to the extension 14 so as toextend throughthe gap 11 ofther magnet 10. The free end of the reed extends terposed in a receiving circuit.

over the extension 15 in spaced relation thereto. The structure formed by the core 13, the coil 12 and the extension 14, the reed 14a and the extension 15 forms a magnetic circuit having a gap 16.

The numeral 17 denotes a stem which is suitably secured to the reed 14a and projects upwardly through the opening 109 in the strip 10f, the upper end of the stem 17 is secured to the diaphragm 7 by means of the nuts 18 or other suitable means. While any suitable winding may be employed, I prefer to wind the coils 10a, 10c and 12 from a-single strand of. wire which is wound on the core 10?) to form a south pole of the strip 10 The winding is continued around the core 10d to complete the coil 106 so as to produce a north pole at the upper end of the core 10d. The wire is then extended to the core 13 and it iswound thereon to form' the coil '12 having a north pole in the strip 15 and a south pole in the strip 14 and the reed 14a. The ends A1 and A2 of the wire A are secured to suitable terminals and are operatively in- It will be seen that an intermittent electrical current such as is formed by the ordinary transmitter' will flow through the coil 10a and 10b and form a powerful electromagnet and that the vibratory reed 14a is positioned through the gap 11 of said magnet. The same current will pass through the coil 12 forming a second magnetic circuit which will act in conjunction with the first named circuit to vi- .brate the diaphragm 7. As the reed 1 1a and the strip 10f are of like polarity, the reed 1 1a will be repelled from the pole strip 10 The upper end of the core 10d and the coil 106 being of opposed polarity, the reed 141a will be "drawn downwardly toward the core 1061.

As the free end of the reed 1.4a projects over the extension 15, the reed will be drawn downwardly toward said extension. is thus actuatedby both the repelling and the attracting forces of themagnetic circuit 10 and is also actuated by the attracting force of the 'magnetic circuit 12 thereby forming a very powerful movement of said reedc14a. As the post 17 is secured to the diaphragm 7, said diaphragm will be actuated in accordance with the impulses flowing through the wire A.

In a modified form of the invention, the strip 10 and 10d and the cores 10b and 10d may be composed of hardened steel, thus forming a permanent magnetic circuit in addition to the electromagnetic circuit 10.

'In Figure 4, I have shown a modified form of the invention in which a permanent horseshoe magnet 20 is employed instead of the electromagnet circuit 12. The free end of the vibratory reed 20 is not positioned over the north pole 20b of the magnet 20, but terminates in spaced relation thereto forming a gap 21. The arrangement is such that The reed 14w changes may be made as come within the scope of the appended claims.

While I have illustrated and described a particular form of winding and have shown the electromagnets connected in series, it is to be understood that any suitable magnetic circuits or connections may be employed and while I have shown the magnets 10 and 12 connected in the same circuit, one of the magnets may be interposed in a separate power circuit if desired.

Having thus illustrated my invention and described the same in detail, what I claim as new and desire to secureby Letters Patent is 1.'In a receiver of the class described, a diaphragm, an electromagnet, a vibratory reed forming a pole piece of said magnet, said reed havingthe end free and arranged to be actuated by energizing said magnet, means operatively connecting the intermediate portion of said reed to said diaphragm and a second magnet, the intermediate portion of said reed operatively interposed between the poles of said second magnet.

2. In a receiver of the class described, a diaphragm, an electromagnet, a vibratory reed forming a pole piece of said magnet, said reed extending to a point in close spaced relation to the other pole of said magnet thereby forming a gap, said reed arranged to be actuated by energizing said magnet, means operatively connecting the intermediate portion of said reed to said diaphragm and a second electromagnet having a gap, the intermediate portion of said reed'operatively interposed in a gap of said second magnet.

3. In a receiver of the class described, a diaphragm, an electromagnet, a flat vibratory reed forming a pole piece of said magnet, said reed having a free end terminating in close spaced relation to the other pole of said magnet thereby forming a gap, said reed arrangedfto be actuated by energizing said magnet; means operatively connecting said reed to said diaphragm ata point intermediate the length of said reed; a second electro magnet having a gap, said reed operatively interposed in the gap of said second magnet with sa1d point of connection disposed in sa1d second named gap and means to operatively interpose the first named magnet in a receiving circuit and means to energize the second named magnet.

4. In a receiving apparatus of the character described, a diaphragm, an electromagnet having a flexible pole piece extended to a point in close spaced relation to the other pole thereof, said pole piece adapted to be actuated by energizing said magnet, a stem connecting said reed to said diaphragm, a second electromagnet having a gap, the cen tral portion of the flexible pole piece of the first named magnet operatively positioned in the gap of said second named magnet, means to operatively interpose one of said magnets in a receiving circuit and means to energize the other magnet.

5. In a receiver of the class described, in combination, a casing, a diaphragm operatively mounted therein, an electromagnet having a flat vibratory pole piece positioned in parallel relation to said diaphragm, said pole piece adapted to be actuated by said magnet, a stem connecting said pole piece to said diaphragm, a second magnet, the said pole piece positioned between the poles of the second magnet and means to operatively interpose the first named magnet in a receiving circuit.

In testimony whereof I have hereunto set my hand.

ARCHIBALD A. DUNCAN. 

